1. Field of the Invention
The present invention relates to a magnetic head assembly and a magnetic disk drive, and in particular, to a magnetic head assembly and a magnetic disk drive for controlling the posture of a magnetic head slider with respect to the magnetic disk surface. Further, the present invention relates to a posture control method for a magnetic disk slider.
2. Related Art
Along with an achievement in high-density recording and large capacity of a magnetic disk drive in recent years, low flying of a magnetic head slider has been developed. In order to realize such low flying, technical development relating to an ABS and a suspension has been promoted. For example, Japanese Patent Application Laid-open No. 5-36035 discloses art for reducing the weight of the tip part of a flexure so as to realize high accuracy in positioning. Further, Japanese Patent Application Laid-open No. 5-159262 discloses art for improving the rigidity of a gimbal so as to realize high accuracy in positioning.
Moreover, in a manufacturing process of a magnetic head assembly or the like, in a state where a magnetic head slider is mounted on a suspension, a tilted degree of the magnetic head slider in a pitch direction or a roll direction with respect to the reference surface is measured and the tilted degree is strictly managed to thereby realize low flying.
In recent years, however, high-density recording and large capacity of a magnetic disk drive has been achieved increasingly, so more stable low flying is demanded. Therefore, it is difficult to keep the desired flying amount securely with the art described above. In particular, since the art described above is not for controlling the flying height positively, it is impossible to set the flying height of each device appropriately after assembled into a disk drive. That is, there may be problems that defective reading or writing of data with respect to a disk is caused due to the flying height being too high, or a clash is caused due to the flying height being too low.
On the other hand, although low flying of a magnetic head slider is demanded as described above, it is difficult to detect the flying height. In contrast, if the flying height of a magnetic head slider can be detected, it is possible to improve the quality of products by inspecting the flying height at the time of shipment and taking defective products out according to the inspection result, for example. Alternatively, the detected flying height may be used for properly controlling the flying height of the magnetic head slider, whereby problems of degrading in the accuracy of reading or writing of data and a clash may be solved effectively.
In view of the above, an object of the present invention is to realize stable reading and writing of data by achieving high accuracy in positioning with respect to a magnetic disk.
In order to achieve the object, one mode of the present invention is a magnetic head assembly comprising: a magnetic head slider for reading and writing information with respect to a rotating magnetic disk; a suspension for supporting the magnetic head slider; and an air flow regulating device for regulating an air flow amount flown in between the magnetic disk and the magnetic head slider along with the rotation of the magnetic disk.
The air flow regulating device includes an extendable/contractible driving device which extends or contracts on the basis of a height from a mounting face, onto the suspension, of the magnetic head slider to a face facing the magnetic disk. In particular, the extendable/contractible driving device extends or contracts on the basis of the height of the main recess plane of the magnetic head slider. Further, the extendable/contractible driving device includes a piezoelectric device.
According to the invention described above, a piezoelectric device which can be controlled to extend or contract with high accuracy is used as an extendable/contractible driving device, and on the basis of the height of the magnetic head slider, the extendable/contractible driving device is controlled to extend or contract so as to protrude or retract from the slider. This enables to regulate the air flow amount, flown in between the magnetic head slider and the disk, for flying the magnetic head, so the extendable/contractible driving device can be operated as an air amount regulating device. By regulating the air flow amount, the dynamic pressure for flying the slider, generated by the flown air, changes, and also the pressing force of the flown air itself for pressing the front end part of the magnetic head slider mounted on the suspension changes as well. Accordingly, the flying height of the magnetic head slider and the posture angle in a pitch direction can be regulated, so that reading/writing processing of signals can be performed with high accuracy by making the distance to the disk closer. In contrast, with the flying height being high with respect to the disk, a clash caused due to a too close distance can be suppressed effectively. Note that the amount of flown air may be regulated by a device other than the extendable/contractible driving device.
In the magnetic head assembly of the configuration described above, the extendable/contractible driving device is preferably provided adjacently on the air inflow side of the magnetic head slider, as an air flow regulating device. Thereby, the size of the air inflow port can be controlled on the basis of the height of the magnetic head slider, enabling to control the amount of flown air easily and securely. For example, although the operation differs depending on the form of the floating surface (flying surface) of the magnetic head slider, it is possible generally to control such that the amount of flown air becomes large and the flying height increases when the extendable/contractible driving device contracts, and the amount of flown air becomes small and the flying height decreases when the extendable/contractible driving device extends.
Further, the extendable/contractible driving device extends or contracts corresponding to the flying height of the magnetic head slider with respect to the magnetic disk. Thereby, if the flying height of the magnetic head slider is low so that a clash may be cause, it is possible to prevent a clash by regulating the amount of flown air so as to increase the flying height. On the other hand, if the flying height is too high so that the accuracy of reading/writing of information is low, it is possible to realize reading/writing of information with high accuracy by regulating the amount of flown air so as to decrease the flying height to thereby realize low flying.
Further, a magnetic disk drive is also provided in the present invention. As a mode thereof, a magnetic disk drive comprises a magnetic head assembly including: a magnetic head slider for reading and writing information with respect to a rotating magnetic disk; and a suspension for supporting the magnetic head slider, and has an air flow regulating device for regulating the air flow amount flown in between the magnetic disk and the magnetic head slider along with rotation of the magnetic disk.
The air flow regulating device includes: an extendable/contractible driving device which is provided adjacently on the air inflow side of the magnetic head slider and extends or contracts on the basis of a height from a mounting face, onto the suspension, of the magnetic head slider to a face facing the magnetic disk; and an extension/contraction controlling device for controlling extending/contracting operation of the extendable/contractible driving device. The extension/contraction controlling device controls the extending/contracting operation of the extendable/contractible driving device on the basis of the height of the main recess plane of the magnetic head slider.
Further, the extension/contraction controlling device controls the extendable/contractible driving device to extend or contract based on posture information indicating the posture of the magnetic head slider with respect to the disk. Here, the posture information is the flying height of the magnetic head slider with respect to the magnetic disk.
Further, the magnetic disk drive includes: a readout signal detecting device for detecting a readout signal, for example, an output voltage value thereof, from the magnetic disk in the magnetic head slider; and a flying state identifying device for identifying the flying state of the magnetic head slider with respect to the magnetic disk as the posture information, based on the readout signal detected.
According to this configuration, first, when data stored on the magnetic disk is read out in the magnetic head slider, as a readout signal, an output voltage value thereof is detected for example. By inspecting the readout signal, it is possible to identify the flying state of the magnetic head slider easily and appropriately. For example, it is possible to detect such information as whether the magnetic head slider flies at a position capable of reading/writing of data appropriately with respect to the magnetic disk, according to presence or absence of the output voltage value and its intensity. Then, according to the flying state of the magnetic head slider detected, the air flow amount flown in between the magnetic head slider and the magnetic disk, generating the flying force in the magnetic head slider as described above, is controlled to be regulated. Thereby, the flying height of the magnetic head slider can be regulated, so it is possible to perform reading/writing of data with high accuracy.
Further, as a configuration for regulating the flying height of the magnetic head slider, the magnetic disk drive includes a slider flying height controlling device for controlling the flying height of the magnetic head slider according to the identified flying state of the magnetic head slider. The slider flying height controlling device includes a slider distance controlling device for controlling a distance from the suspension supporting the magnetic head slider to the surface of the magnetic disk according to the identified flying state of the magnetic head slider to thereby control a distance from the magnetic head slider to the surface of the magnetic disk. Thereby, according to the detected flying state of the magnetic head slider, the distance between the magnetic head slider and the magnetic disk is controlled by the slider distance controlling device so as to control the gram load of the magnetic head slider, whereby it is possible to regulate the magnetic head slider to have an appropriate flying height.
Further, the magnetic disk drive includes a reference data storing device for storing reference data which has been determined beforehand and is compared with the readout signal, and the flying state identifying device compares the readout signal detected with the reference data, and according to the comparison result, identifies the flying state of the magnetic head slider as the posture information. Alternatively, the magnetic disk drive includes a map data storing device for storing map data indicating the relationship between the readout signal and the flying height of the magnetic head slider, and the flying state identifying device identifies the flying height of the magnetic head slider with respect to the magnetic disk based on the readout signal detected and the map data.
Thereby, it is possible to identify the flying state of the magnetic head slider easily and accurately by setting beforehand, as reference data, values corresponding to readout signals in a flying state where reading/writing of data can be performed accurately and readout signals in an inappropriate flying state, and comparing the readout signal detected with the reference data. In particular, it is possible to identify the flying height easily and with high accuracy by preparing map data in which the relationship between readout signals and the flying heights are set beforehand through experimentations or logical calculations and matching the detected readout signal with them.
Further, the present invention also provides a posture control method for a magnetic head slider. One mode thereof is a posture control method characterized as to regulate the air flow amount flown in between the magnetic disk and the magnetic head slider along with the rotation of the magnetic disk according to the posture of the magnetic head slider. The posture is identified in such a manner that, as a readout signal, an output voltage value thereof is detected from the magnetic disk in the magnetic head slider, and the posture is identified based on the readout signal detected.
Another mode of a posture control method for a magnetic head slider is characterized as to regulate the air flow amount flown in between the magnetic disk and the magnetic head slider along with the rotation of the magnetic disk according to the driving state of the magnetic disk drive.
Further, another mode of a magnetic head assembly of the present invention comprises: a magnetic head slider for reading and writing information with respect to a rotating magnetic disk; a suspension for supporting the magnetic head slider; and an air flow right-and-left balance regulating device for regulating a right-and-left balance of the air flow flown in between the magnetic disk and the magnetic head slider along with the rotation of the magnetic disk.
In particular, the air flow right-and-left balance regulating device includes a plurality of extendable/contractible driving devices which extend and contract on the basis of the height from a mounting face, onto the suspension, of the magnetic head slider to a face facing the magnetic disk and are arranged in parallel toward a flowing direction of air flown into the magnetic head slider. Further, the plurality of extendable/contractible driving devices extend or contract independently, according to the roll of the magnetic head slider.
With the configuration described above, by extending or contracting each of the extendable/contractible driving devices positioned separately in parallel, the air flow amount flown in between the magnetic head slider and the magnetic disk can be changed by each mounting row of the extendable/contractible driving device in a right and left direction of the magnetic head slider. Thereby, the flying height in the right and left direction can be changed, so the posture in a roll direction of the magnetic head slider can be controlled as well. Accordingly, by extending or contracting each extendable/contractible driving device according to the current rolling state of the magnetic head slider, it is possible to control the magnetic head slider to have a posture optimum for performing reading/writing of information and capable of suppressing a clash.
Further, another mode of the magnetic disk drive comprises a magnetic head assembly including: a magnetic head slider for reading and writing information with respect to a rotating magnetic disk; a suspension for supporting the magnetic head slider, and has an air flow right-and-left balance regulating device for regulating a right-and-left balance of the air flow flown in between the magnetic disk and the magnetic head slider along with the rotation of the magnetic disk.
The air flow right-and left balance regulating device includes: a plurality of extendable/contractible driving devices which are provided adjacently on the air inflow side of the magnetic head slider, and extend or contract on the basis of the height from a mounting face, onto the suspension, of the magnetic head slider to a face facing the magnetic disk, and are arranged in parallel toward a flowing direction of air flown into the magnetic head slider; and an extension/contraction controlling device for controlling extending/contracting operations of the plurality of extendable/contractible driving devices independently.
The extension/contraction controlling device controls the plurality of extendable/contractible driving devices independently, based on posture information indicating the posture of the magnetic head slider with respect to the magnetic disk. Further, the posture information is a roll of the magnetic head slider.
The magnetic disk drive of the configuration described above is capable of performing posture control of the magnetic head slider similarly to the case of the magnetic head assembly described above. In particular, by controlling the extendable/contractible driving device to extend or contract by the control device actively, positioning control of the magnetic head slider can be performed with high accuracy according to the operating state of the magnetic disk drive, so it is possible to stabilize the operational state.